Development of earth-abundant $Cu_2ZnSnSe_4$ solar cells on flexible titanium substrate

Abstract

Flexible thin-film solar cells are an essential task of second-generation solar cells. In this study, the solar cell was fabricated by using $Cu_2ZnSnSe_4$(CZTS) consisted of earth-abundant elements as an absorber layer and Titanium (Ti) foil as a substrate to make low cost flexible thin-film solar cell. In the process, the CZTS deposition conditions were adjusted to control the secondary phases and defects. To analyze the effects of Soda-lime glass and Ti substrates on CZTS solar cells, the characteristics of the two solar cells were compared. Ti substrates have found that higher temperature annealing is required. As a result, it was observed that there is a deeper energy trap and lower carrier concentration in the CZTS solar cell of the Ti substrate by comparing the characteristics of the solar cells of two optimized substrates. This is expected to be due to the lack of sodium. J-V and external quantum efficiency (EQE) measurement, capacitance-voltage (CV) measurements, and admittance spectroscopy (AS) measurements were used for analysis.